Odorless solvent manufacture



Sept. 11, 1956 w. A. JONES EFAL 2,762,853 ODORLESS SOLVENT MANUFACTUREFiled June 8, 1954 ODORLESS SOLVENT l7 Z'Er QQ LATE HYDRO- FININGREACTOR 8 I5 7 BOTTOMS L v l RECYCLE ACID OLEF'INS lfl 2 I fi 1 WILLIAMA.JONES CURVI N H. STEIN SOFARAFF'INE INVENTORS 8Y7, [Z ATTORNEY UnitedStates Patent onoRLEss SOLVENT MANUFACTURE William A. Jones and CurvinH. Stein, Sarnia, Ontario, Canada, assiguors t Esso Research andEngineering Company, a corporation of Delaware Application June 8, 1954,Serial No. 435,218

3 Claims. (Cl. 260-6834) The present invention is concerned with theproduction of substantially odorless hydrocarbon solvents. The inventionis more particularly concerned with the preparation of hydrocarbonsolvents from a heavy alkylate prod uct. In accordance with the. presentinvention a high quality substantially odorless hydrocarbon solvent issecured by distilling a heavy alkylate product followed by hydrofiningthe desired fraction.

It is well known in the art to prepare hydrocarbon solvents by variousprocedures. For instance it is known that odorless hydrocarbon solventsare mainly isoparalfins and parafiins boiling in the range from about350 to 450 F. However, when these solvents are prepared from an alkylatematerial, they are characterized by a rancid odor. This odor is noteliminated during distillation to separate solvents of the desiredboiling ranges and distillation actually causes the solvents to acquireadditional rancid odor which cannot be removed by ordinary treatingmethods such as caustic washing, acid washing or percolation throughclay. In accordance with the present invention this rancid odor isovercome by hydrofining the desired alkylate cut.

The process of the present invention may be fully understood byreference to the drawing illustrating one embodiment of the same.

Referring specifically to the drawing, a feed stream comprisingisoparafiins' such as isobutane or isopentane' is introduced intoalkylation zone 1 by means of feedline 2. Olefins such as C2-C5monoolefinic hydrocarbons are introduced into the isoparaflins by meansof line 3 while acids are introduced into alkylation zone 1 by means ofline 4. Preferred reactants comprise isobutane and C4 olefins. Recycleis illustrated by means of line 5. The alkylation operation comprises aconventional one wherein the. ratio of isoparaflins to olefins ismaintained relatively high in order to prevent polymerization of theolefins, while the concentration of the acid, preferably sulfuric acid,is in excess of 88%, preferably in excess of 96%. Temperature conditionsare in the range from 30 F. to 100 F., while the time of. reaction isgenerally about -60 minutes. It is to be understood that alkylation zone1 may comprise any suitable number and arrangement of stages, settlingzones and the like.

The alkylate product is withdrawn from alkylation zone 1 by means ofline 6 and introduced into a distillation zone 7 wherein a lightalkylate product boiling in the range below about 350 F. is segregatedby means of line 8. Hydrocarbon constituents boiling below the gasolineboiling range are removed overhead by means of line 9. A heavy alkylateproduct boiling above about 350 F. is removed by means of line 10 andintroduced into a distillation zone 11. Temperature and pressureconditions are adjusted in distillation zone 11 to remove as a sidestream by means of line 12 an alkylate product boiling in. the rangefrom about 350 to 400 F. A second side stream boiling in the range from400 to 450 F. is removed by means of line 13. Hydrocarbon constituentsboiling below about 350 F. are removed overhead by means of line 14while constituents boiling above about 450 F. are removed by means ofline 15. The alkylate products of either or both lines 12. and 13 may beprocessed in accordance with this invention.

In accordance with the present invention the segregated alkylate streamintended for use as an odorless solvent is passed to hydrofiningreaction zone 16 to be subjected to mild hydrofining conditions asdescribed hereinafter. As will be appreciated, the stream of line 12 ispassed through a heating zone prior to entrance to the hydrofining zoneto raise the stream to hydrofining temperatures. The finished odorlesssolvent is removed by means of line 17 as a high quality productsolvent.

It is essential, in practicing the present invention that theliydrofining operation conducted on the alkylate fraction be a mildhydrofining operation. This is to be distinguished from conventionalhydrofining operations heretofore practiced in the art. Such hydrofiningoperations have been employed at pressures from 200 to 500 lbs. persquare inch, at feed rates of .5 to 2.0 volumes of feed' per volume ofcatalyst per hour. Relatively high rates of hydrogen recycle have beenemployed, for example, 2,000 to 4,000 standard cubic feet per barrel inorder to vaporize the feed, to control heat developed by hydrogenaddition and prevent carbonization of the catalyst. Likewise,temperatures above 700 F. have been used, normally, in order to vaporizethe feed, convert high molecular weight hydrocarbons to lower molecularWeight or to remove high percentages of sulfur. Under these conditions,hydrogen consumption has generally been in the range of 150 to 600standard cubic feet per barrel of feed for desulfurization and above1,000 cubic feet per barrel for hydrogenation-cracking. This relativelyhigh consumption of hydrogen has made the process expensive to operate,so that where ample supplies of crude oils containing light hydrocarbonsexist, its application has been limited to the treatment of relativelyhigh sulfur stocks which could not be desulfurized by any otheravailable treating operation.

The mild hydrofining condition of the present invention may be carriedout by lowering the temperature,

. increasing the feed rate per volume of catalyst or by using a lessactive catalyst. In accordance with the present invention thetemperatures used are in the range from about 300 to 700 F., preferablyin the range from about 500 to 650 F. Pressures employed are in therange from 50 to 1000 lbs. per square inch, preferably in the range fromabout 200 to 800 lbs. per square inch. The feed rates, in accordancewith the present process, are in the range from about 0.5 to 10 volumesof liquid per volume of catalyst per hour. Preferred feed rates are inthe range from 1 to 5 v./v./hr. The hydrogen in the gas to thehydrofining unit may vary from 50 to This means that, for example,dilute hydrogen from a hydroformer can be used in the hydrofiningprocess. Since the treatment is effective with the oil maintained atleast partially in the liquid phase, hydrogen recycle rates above 1,000cubic feet per barrel of feed oil have not been found necessary toprevent carbonization of the catalyst.

The catalyst utilized in the present operation may comprise knownhydrofining catalysts, as for example, nickel on kieselguhr, platinum onalumina, molybdenum oxide or sulfide on alumina, cobalt molybdate onalumina, nickel-tungsten sulfides and other catalysts known in the art.While the preferred catalyst of the present invention comprises cobaltmolybdate on alumina, catalysts such as nickel on kieselguhr andnickel-tungsten sulfides have been found. effective in the mildhydrofining operation to be conducted in accordance with this invention;In the preferred catalyst the amount of cobalt oxide is about 4% to 5%and of molybdenum oxide about 8% to 10% based on the Weight of thealumina. The catalyst is prepared by known methods, such as byimpregnation of the alumina with a water-solution of cobalt molybdate orof other water-soluble salts of cobalt and molybdenum followed byheating to convert the cobalt molybdate and the salts to their oxides.The catalyst may also be prepared by coprecipitation of aluminum, cobaltand molybdenum hydroxides by addition of an ammoniacal solution ofammonium molybdate to an acid solution of a cobalt salt and an aluminumsalt followed by water Washing and by heating to convert to the oxides.Catalysts prepared by dry mixing of alumina, cobalt oxide and molybdenumtrioxide may also be used. The catalyst may be used in the form ofpills, broken stones or other suitable forms.

The mild hydrofining may be carried out by contacting alkylate andhydrogen with the catalyst either by batch or by continuous flowoperation. In batch operation the oil and the desired proportion ofcatalyst to oil, under a hydrogen atmosphere at the required pressure,are heated to the required temperature in a bomb or autoclave and mixedtogether for the required time by stirring or by shaking.

In continuous operation, the oil and hydrogen are contacted withcatalyst by continuous flow through a vessel packed with catalyst. Theoil feed to the reactor is preheated to the required temperature bymeans of a furnace or similar means. Hydrogen may or may not be heatedprior to feeding to the reactor depending on the quantity used. Thedegree of contact of oil saturated with hydrogen with the catalyst isdetermined by the ratio of the oil flow rate to the catalyst volume.

After the hydrofining process has been carried out by either the batchor continuous technique described, a small portion of the lighterreactor effluent is separated. This may be achieved in a simple still inwhich pressure is dropped sufiiciently to flash about l2% of thehydrofined alkylate product. Hydrogen is thereby separated from thealkylate product together with about 90% to 95% of the by-product gasesformed as a result of the hydrofining. The disengaged hydrogen may bepurified for recycle.

The residual traces of HzS in the hydrofined product may be eliminatedif necessary by caustic washing. A single stage treatment using about 2to 5 weight percent of about 5 B. caustic is satisfactory.

It is to be understood that the mild hydrofining conditions of thepresent invention are secured by the selection of the catalyst and byadjustment of the space velocity, temperature and pressure. Forinstance, if a relatively high liquid feed rate is used as compared tothe amount of catalyst present (high space velocity) the highertemperature range indicated may be employed. On the other hand, if avery active catalyst is used, it may be desirable to use a relativelyhigh feed rate together with a relatively low temperature. The mildhydrofining conditions of the present invention are best measured by theamount of hydrogen consumed. In the process of this invention, thehydrofining conditions are adjusted to secure a positive consumption ofhydrogen but not more than 10 standard cubic feet per barrel notincluding mechanical losses. There is substantially no change in theinspections of the alkylate so that the hydrofining operation does notappreciably alter the viscosity, specific gravity, boiling range, oraniline point of the alkylate. Nevertheless, this mild hydrofiningtreatment results in the desired improvement in the odor of the alkylateby a mechanism which is not fully understood.

Another means of establishing the mild hydrofining conditions to beemployed is to so adjust the temperature, pressure, and feed rates sothat over 98% of the hydrofined products is of the same flash point asthe original feed. Generally, conditions are so adjusted that less than2% of the hydrofined constituents are converted to lower boilingconstituents. The following examples demonstrate the utility andoperability of this invention:

Example 1 A sample of the 350 to 400 F. cut of batch distilled heavyalkylate was given a 10 volume percent 10 B. caustic wash andthenhydrofined under the following conditions:

Pressure 600 p. s. i. g.

Temperature 550 F.

Catalyst UOP Nickel, 1 vol. percent on oil charge. Time 10 hours.

This treatment removed the rancid odor present in the caustic washedfeed.

Inspection Feed Product Odor Unsatisfactory-. Satisfactory. API GravityV 54.0. 64.2. Wt. Percent Sulphur 0.002 0.002. Aniline F 181 187. K. B.S 26. R. I. 20 C- 1.4243. Bromine No Less than 1. AS'IM Distlll IBP 350.

FBP 378.

This hydrofining treatment removed of the feed stock. Inspections offeed and product are:

the rancid odor Inspection Feed Product Unsatisfactory" Satisfactory.64.0- 54.5. Flash Pt;., "F 124. Color Saybol +30. Wt. Percent Sulnhur0.002.. 0.002. Bromine N 2.8.. Less than 1. Aniline Pt; F 181 181.5. R.I. 2 1.4247" 1.4244. ASTM Distillation:

IBP 350 350. 10% 354 354. 50% Wt 359. 90%; 369"; 366. FBP 380 378.

The data of these examples, shows that the rancid odor of an alkylateproduct cannot be eliminated by caustic Washing. However, the odor canbe eliminated by a mild hydrofining treatment of the characteridentified.

What is claimed is:

1. Improved process for the preparation of a high quality essentiallyodorless hydrocarbon solvent which comprises alkylating an isoparaffinwith an olefin, segregating a fraction of the alkylate product boilingin the range from about 350 to 450 F., and thereafter mildly hydrofiningsaid fraction at conditions to secure 'a positive consumption ofhydrogen but less than 10 standard cubic feet per barrel of product. 7 I

2. A process for preparing high quality..alkylate in which a heavyalkylate fraction. is hydrofined at a temperature ofabout 3100? to 700F., at a pressure of. about 50 to 1,000 1bs. per square inch in thepresence of excess hydrogen and in contact with a hydrogenation catalystin a manner to secure a hydrogen consumption less than 10 5 standardcubic feet per barrel of feed whereby the normally rancid odor of thealkylate is removed with substantially no change in other properties.

3. The process of removing undesirable odor of a heavy alkylate boilingwithin the range of about 350 to 450 F., comprising hydrofining saidalkylate to secure a positive hydrogen consumption of not more than 10standard cubic feet of hydrogen per barrel, segregating H2 along withother gaseous by-products and less than 2% of the lighter alkylateconstituents, and caustic Washing the final alkylate product.

References Cited in the file of this patent UNITED STATES PATENTS

1. IMPROVED PROCESS FOR THE PREPARATION OF A HIGH QUALITY ESSENTIALLYODORLESS HYDROCARBON SOLVENT WHICH COMPRISES ALKYLATING AN ISOPARAFFINWITH AN OLEFIN, SEGREGATING A FRACTION OF THE ALKYLATE PRODUCT BOILINGIN THE RANGE FROM ABOUT 350* TO 450* F., AND THEREAFTER MILDLYHYDROFINING SAID FRACTION AT CONDITIONS TO SECURE A POSITIVE